This invention relates to a fractionation tower and sidestream stripper therefor.
Many distillation processes, such as atmospheric and vacuum distillation of crude oils, produce multiple sidestream products. Often, such sidestreams are stripped in respective strippers using steam, with the steam and stripped-out vapors being discharged into the main distillation tower at or above the point where the sidestream is withdrawn. For convenience of layout and compactness, the strippers for two or more sidestreams are often stacked on top of each other in one shell. However, no fluid connection exists between the strippers, so that each has its own individual strip gas supply and exit points.
The purpose of each stripper is to remove light components from the sidestream product and thus to improve the separation between neighboring sidestreams. However, in practice the stripping process is not very selective and, even with a large amount of steam and a large number of theoretical stages, only moderate improvements in the separation between sidestreams can be made.
It would be desirable to simplify the constructural arrangement and/or improve the operational efficiency of distillation processes.